4331721521 has 2 divisors, whose sum is σ = 4331721522. Its totient is φ = 4331721520.

The previous prime is 4331721509. The next prime is 4331721551. The reversal of 4331721521 is 1251271334.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 2924646400 + 1407075121 = 54080^2 + 37511^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-4331721521 is a prime.

It is a super-2 number, since 2×4331721521² = 37527622670989106882, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (4331721551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2165860760 + 2165860761.

It is an arithmetic number, because the mean of its divisors is an integer number (2165860761).

Almost surely, 2^4331721521 is an apocalyptic number.

It is an amenable number.

4331721521 is a deficient number, since it is larger than the sum of its proper divisors (1).

4331721521 is an equidigital number, since it uses as much as digits as its factorization.

4331721521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5040, while the sum is 29.

The square root of 4331721521 is about 65815.8151282805. The cubic root of 4331721521 is about 1630.1222537434.

Adding to 4331721521 its reverse (1251271334), we get a palindrome (5582992855).

The spelling of 4331721521 in words is "four billion, three hundred thirty-one million, seven hundred twenty-one thousand, five hundred twenty-one".